How sturdy are pocket hole joints

[tool-me-up]

as title, are they any good or are they for decorative things mainly?
I know glue would improve strength but how do they stack up to tenon joints and the likes?

 

[RogerP]

Test here ..

http://woodgears.ca/joint_strength/

 

[Lord Kitchener]

You need to consider the overall design and what stresses the joint is likely to be subjected to, rather than a single joint in isolation.

Having said that, yes, they are more than strong enough for most applications. I wouldn't use them for joining table legs to aprons, but for making boxes etc they are excellent.

 

[Grahamshed]

I have seen several tests showing them to be much stronger than you might think. It is the cost of the jig that surprises me.

 

[Glynne]

I used pocket hole joints on this small table in the porch.

It was always going to be fixed to the wall (as you can see) but it currently has a huge plant pot stood on it and occasionally Grandson gets sat on it to put his wellies on.
Glynne

 

[Eric The Viking]

I have huge respect for Matthias Wandel, but I think there is one error in his measurement of pocket hole joints: on the web page he says he used drywall screws, and his jig is home made (fair enough in his case!).

Drywall screws have a flat, trumpet-shaped head, so that they can be set in plasterboard (drywall). They are popular for that purpose, but they're not the Robertson screws that Kreg et al supply. The Robertson screws have a flat back to the screw head. When you tighten them up they compress the wood fibres, rather than sink in. I think the drywall screws will to an extent work like countersunk ones, spreading the fibres and sinking in.

The results he has for pocket hole joints aren't shabby - a little less strong than properly glued dowels and a fair bit weaker than mortice+tenon, but if he'd used the recommended screws and screw heads (Kreg recommend different thread forms for softwood,hardwood and man-made boards), the results would have been even better.

If you look at the section titled "retesting with Maple", it's clear that a flat surface for the screw head (washers in this case) really helps. The mechanical failures were either the wood surrounding the pockets, or the screw heads pulling in. I've a suspicion that the Kreg jig would do a better job, too, as it allows for wood thickness and isn't just an angle guide for cutting the pockets.

Finally, I note his pocket hole and screwed joints don't appear to also be glued. I can only guess, but I think a proper glued joint would be notiecably stronger too. These things would make it at least as strong as a dowelled joint for the same overall contact area.

If I've misunderstood MW or his pocket hole jig I apologise

E.

 

[Stu_2]

I've recently started using the pocket-hole method, and really like it. Quick and strong. I've mainly used them for storage solutions, boxes and draws etc. Also used them for contructional work such as pipe covers/protectors. I went for the Kreg K4 Master System, and am very pleased with it. Bit expensive, but works very well. I need to build some pretty large cabinet doors soon, and will be using this method for sure.

These UJK pocket-hole clamps are also a superb addition, although they don't work with the smaller holes produced by the Kreg Micro jig. That said, I'll be modifying a couple in the near future as I've used the Micro jig nearly as much as the standard one.


Cheers
Stu

 

[Roughcut]

I always hated things that had been assembled with the pocket hole screw method.
To my eye it looked ugly.
But looking back I think my opinion came from seeing pieces that had been assembled so that the pocket holes were not hidden well enough.
I have been using the Kreg K4 jig for about 6 months and find it extremely easy to use and fast.
However it is important to plan out your work piece to ensure that the pocket holes will be hidden from view and so aesthetically pleasing.
As far as strength is concerned I usually use more screws than is probably required.......just to make sure.

 

[Reggie]

I bought the one from rutlands that was £30 reduced from £70 http://www.rutlands.co.uk/sp+pocket-hol ... -kit+DKPHG

It's not quite as good as I expected but I can see how to improve it to make it (almost) as good as anything else, it looks a bit like the trend jig but the trend jig is slightly better.

For a start, it's only set to give centred pockets on 19mm/ 3/4" stock, you can easily remedy that for stock <19mm by shimming the work piece until it makes 19mm combined, so for 12mm stock, add 7mm of packing on the hole side.

For stock larger than 19mm you need to adjust the height of the guide holes, on other similar models to the rutlands dakota, the height is adjustable because the part holding the guide holes to the rest of the jig has a slot, the rutlands one doesn't However, it is held in place by 2 allen bolts underneath which give you about 6mm of height adjustment, which isn't particularly useful but it does mean that you can remove it and add a 'solution' between the base and the guide hole mechanism, my solution would be something like a simple hard wood/aluminium spacer and longer allen bolts.

I've just double checked on the rutlands website and the picture of my jig isn't quite the same as the one in the picture, there is a set of 4 holes missing, you can see one of them in the picture on the website just behind the base of the clamp mechanism, they're necessary for adjusting the clamp so that it will take 1 and a 1/2" stock. I've just had a nice phone call to nice lady at rutlands who offered me a full refund, it appears that they themselves have only become aware of the design change themselves on stock that came in last week :-(

I can see 2 solutions to this:
1. Get a set of 4 holes tapped
2. shorten the adjustment bolt on the clamp head. It's unnecessarily long, and it's still got a 1/2" or so that protrudes out of the end of the tube when it's screwed in as far as it will go, that will probably be enough, I'll test this method first and report back my findings.

I'm really reluctant to get a refund, for £30 + a bit of tlc, it can be whipped right into shape and be almost as good as anything else.

 

[Eric The Viking]

I looked at the Rutlands ones, and stayed away. Have a look at proper Kreg or the Axminster UJK ones.

I have Kreg but I got a good look at the UJK one in Axy's shop: it looks pretty well made. Also, both it and the Kregs adjust for the stock thickness properly, which I think is essential. The cheaper ones don't seem to have a facility to do this.

I'm not a commercial user, but I appreciate the thought that's gone into the Kreg one every time I use it.

E.

 

[Benchwayze]

Kreg joints are stronger than you might think. But you have to be sure you drill to the correct depth, use the right screws, and in a rail say 4" wide (Sorry 100mm) you might be wise to use three or maybe four screws. (Or use an Em and Tee!)

The main advantages; they do away with clamping, they are quick to do. and they are fine for 'utilitarian' jobs.

On the minus side, you do need to clamp the parts together, so they don't shift when drilling. I suppose you could get away with using ordinary, one-handed clamps for this job, but I found it was much better to use the Kreg designed 'mole-grip' type clamp.

HTH

 

[tool-me-up]

I was interested by the kregs, its the all extra crap that puts me off, screws drivers etc.
I was looking at a much cheaper dowelling jig - fitting a collar to a small drill bit so I can put a 2mm drill through a 6mm hole and just using normal washer head screws.

Ive never used pocket holes before, they do look quite nifty, but sometime I think by the time ive set the jig up found messed about clamping it still and drill the pilots , then change bits and screw it together id be nearly finished a mortice and tenon if I did it on a router table or table saw.

 

[Eric The Viking]

I suggest you try it - it's fast and pretty easy. There aren't any unnecessary bits in the Kreg kit that I've noticed.

 

[Benchwayze]

You can use washer head screws if you wish. Just buy the basic jig, and get washer head screws and a driver-bit to suit. But the Kreg screws are the most convenient. (And expensive.) But look what you'll save on glue and cramps!

You'll find two cordless drills (18v for preference) useful too.

 

[tool-me-up]

Definitely something I will look into - im about a hundred steps ahead of myself at the minute.
I still need to sort out something to work in! My current workspace is littered with engines car parts and no wood benches of any sort.

 

[Reggie]

the rutlands jig is mostly reasonable I think, ok, the height adjustment is something they could've done but it's something I can adapt myself and won't cost me £40 either. it's also possible to take the jig apart so that you get a single drill guide, which can obviously be place and clamped to suit any thickness wood and screw, so it's a lot more versatile than it looks.

I really like some of the kreg stuff, the pocket hole stuff looks really good but personally I can't justify the extra cost.

 

[Stu_2]

Being able to adjust for material thickness is vital. If the jig is for occasional use, or working with the same thickness of material all the time, the UJK one would be ok, and it’s build quality looks very good. However, once you've used pocket-holes, you'll probably start using them more and more, in which case you'd appreciate the speed and flexibility of the Kreg. The UJK jig is not as quick to adjust, and this could become frustrating when testing for different material thickness and type. Drilling depth adjustment is also very important, and the Kreg way is better, especially when using custom depths. Hard to explain, and maybe not so obvious until you start joining different thickness material, but a very important consideration.

You'll also want to remove the guide block from the jig if you need to attach it to larger or immovable pieces of material. It takes seconds with Kreg, but you’ll need to dismantle the UJK jig to achieve this (4 screws from underneath).

Also, for working with thinner material, or if you need smaller footprint pocket-holes, Kreg do a ‘Micro’ block (about £36), which slots straight into their standard holder. I’ve found really useful when working with 12mm ply. The standard Kreg screws are still used, although I find it best to use their cap head screws when working with these smaller holes.

I’m using the K4 Master System kit, which can be had for £98 (Workshop Heaven) now that the K5 has been released. I actually prefer the K4 to the newer K5, due to the clamp design, and you get a lot more for money with the K4MS. Some people make their own, but I didn’t have time to fanny about for hours on something that still wouldn’t be anywhere near as nice and easy to use as the Kreg.

By the way, I’ve no connection with any manufacturer or retailer.

Hope this helps a bit

Cheers
Stu

 

[shed9]

+1 for the Kreg K4

I did my research between the UJK, Rutlands and the Kreg version. Ironically I was originally put off by the Kreg due to the higher cost and plastic construction, however the construction is spot on, its a very flexible system and well worth the money.

I've read countless threads on how the UJK and the Rutlands devices either need modification, do not quite cut it or end up being a regretted purchase, however I have yet to read of major issues with the Kreg system. A big advantage with the K4 is the ability to remove the drill cartridge and clamp it straight onto wood in situ.